Signal tracking system and method

ABSTRACT

The objective of the present invention is to propose a system and a method for determining the origin of a signal received by a pay television subscriber in a given region.  
     This objective is achieved by a system comprising encryption means located at a main operator, transmission means of an encrypted video signal towards at least one local operator, and decryption means at the local operator, characterised in that the decryption means comprise identification means replacing all or part of the decrypted video signal with an identification signal characterising the decryption means.

[0001] The present invention is of the field of information signaldistribution by means of several intervening parties, particularly todetermine in an indisputable manner the origin of this signal.

[0002] In the case of a pay television broadcasting, several interveningparties cooperate so that the subscribers can receive the desiredemissions.

[0003] Amongst these intervening parties we find firstly the main ornational operators who offer the important television channels. Itshould be known that a same channel can be offered by more than onenational operator.

[0004] These national operators can either be the creators of thischannel or they can sign broadcasting contracts with other local orforeign broadcasters.

[0005] These national operators thus offer a service palette to localoperators, the latter being connected to a certain number ofsubscribers.

[0006] A local operator can be active in several regions and thecontracts binding this operator to a national operator are generallybased on the number of subscribers to which the channel will bebroadcasted or according to a geographical definition.

[0007] Thus it is possible for a local operator to sign a broadcastingcontract for a region A although this operator broadcasts also inregions B and C.

[0008] Then it exists technically a possibility for this operator toalso broadcast in the regions B and C without the national operatorbeing able to intervene.

[0009] This is particularly the case in the case that the illegallybroadcasted channel in the region B is also offered by another nationaloperator through another local broadcaster. It is then difficult for themain operator to know if the signal received in the region B comes froma contract signed only for the region A or if it comes from anothernational operator. In fact, each subscriber can be connected to morethan one local operator, the latter being supplied by many nationaloperators.

[0010] It is well known that the national operators transmit theirsignals to the local operators in encrypted form. For the decryptionoperation, decryption means are supplied by the national operator, thesemeans comprising a decryption module and a smart card, the latter beingin charge of ensuring the access control. Once the signal is decryptedby the decryption means, the local operator can dispose of it as itlikes. It is then allowed for the local operator to compose itstelevision bouquet with a selection of channels subscribed from severalnational operators.

[0011] The aim of the present invention is to propose a system and amethod for determining the origin of the signal received by a subscriberin a given region.

[0012] This objective is achieved by a system comprising encryptionmeans located at a main operator, transmission means of an encryptedvideo signal towards at least one local operator, and decryption meansat the local operator, characterised in that the decryption meanscomprise identification means replacing all or part of the decryptedvideo signal with an identification signal characterising the decryptionmeans.

[0013] By identification signal we understand a visual signature addedto any region of the screen. It can have the form of a text field at thebottom of the screen or a background overlaying the real image.

[0014] When this signal is added to the video signal, all thesubscribers to whom the channel is broadcasted will see anidentification message appear on their screens.

[0015] In order to be able to trace the origin of the data transmittedto a subscriber this message will contain an identifier specific to thedecryption means responsible for the decryption of the main operator'ssignal.

[0016] The latter may thus prove that the channel available for anygiven subscriber is the result of its transmission towards a given localoperator.

[0017] According to our previous example, a subscriber of the region Bserves as a test to determine if the contract with the local operatorhas been respected. If the identification message appears on his/herscreen the local operator has not respected its contract that waslimited to the region A.

[0018] The invention will be better understood with the help of thefollowing detailed description which refers to the annexed FIGURE whichis given as a non-limiting example, in which the single FIGURErepresents a system of pay television broadcasting with severalintervening parties.

[0019] On the left are two main operators OPP1 and OPP2. These operatorspropose their broadcasting channels to all the local operatorsrepresented by OPL1 and OPL2.

[0020] The link between the main operators and the local ones is done byexample by satellite or by cable. Many local operators can receive thesesignals and due to this it is necessary to encrypt the data in order tocontrol the use.

[0021] To this effect a decryption module MS is placed at the localoperator and is in charge of decrypting the signal encrypted by the mainoperator. This module has the form of a pay television decoder and islinked to a security module that has the form of a smart card. This cardcontains the keys that are necessary for the functioning of thecryptographic processor contained in the decryption module.

[0022] In this way, each main operator that signs an agreement with alocal operator also installs such a decryption module MS in the premisesof the local operator. The signal coming out of the decryption module MSis in plaintext and no other control at that stage can be carried out bythe main operator.

[0023] The local operator composes its offer, which is an assembly ofseveral channels acquired from several main operators (OPP1, OPP2), andencrypts it according to a protocol and means that are specific to it.

[0024] This new signal is then broadcasted by different means, forexample by cable or by radio-relay network, to the target regions (RA,RB, RC) of this operator.

[0025] At the subscriber's end there is the final decoder (STB) incharge of decrypting the signal of the local operator.

[0026] According to our example of FIG. 1, the region B (RB) is suppliedby two local operators either the operator OPL1 or OPL2.

[0027] The main operator OPP1 signs a broadcasting agreement of channelS with the operator OPL1 for the region A (RA). It should be noted thatthis channel is equally proposed by the main operator OPP2 that signs anagreement with a local operator OPL2 for the region E (RE).

[0028] In the case where the channel S is also broadcasted in the regionB, it is difficult for the main operator OPP1 to know if a decoder STBreceives the channel S from the operator OPL1 or from OPL2, the latteralso being able to broadcast in other regions the channel S.Furthermore, it may happen that the decoders STBy and STBx are in factthe same decoder, the latter having the subscription rights from bothlocal operators.

[0029] This configuration is even more complicated by the fact that thelocal operator OPL2 can sign a broadcasting agreement for the region Beither with the operator OPP1 or with the operator OPP2. The simple factof adding a logo on the signal brodcasted by a main operator does notallow to determine if the agreements for each region are beingrespected.

[0030] This is why, according to the invention, the main operator OPL1sends a command to the decryption module MS1 so that a signalidentifying this module is added to the screen of the decoders thatreceive the signal issued from this decryption module MS1.

[0031] This identification generally comprises the identification numberof the decryption module and the number of the security module (smartcard). In this way these numbers prove indisputably the origin of thechannel S from a decoder for a given region. This identification lastsseveral seconds in order not to disturb the subscriber.

[0032] This duration can be managed either by the decryption moduleitself or by a command sent by the main operator to disactivate thisfunction.

[0033] According to a first embodiment, this signal replaces the bottompart of the image with these indications of alphanumeric type.

[0034] The region modified by this information can be randomly chosen toprevent the local operator from detecting the identification mode andfrom replacing the corresponding part with an advertisement text.

[0035] According to a second embodiment, the identification data areadded in the background on the image. It is then impossible for thelocal operator to hide this information.

[0036] According to one embodiment the command sent by a main operatoris called global, that is that it makes react all the decryption modules(MS1, MS1′).

[0037] According to another embodiment the command sent by a mainoperator is called selective, that is that it makes react only thedecryption module that is called.

1. System for identifying the origin of a signal broadcasted to asubscriber, comprising encryption means located at a main operator,transmission means of an encrypted video signal towards at least onelocal operator, and decryption means located at this local operator,this local operator having from then on the decrypted signal forbroadcasting to its subscribers, characterised in that the decryptionmeans comprise substitution means replacing all or part of the decryptedvideo signal with an identification signal characterising the decryptionmeans.
 2. System for identifying the origin of a signal according toclaim 1, characterised in that the decryption means comprise adecryption module and a security module.
 3. System for identifying theorigin of a signal according to claim 2, characterised in that theidentification signal comprises an identifier of the decryption moduleand an identifier of the security module.
 4. System for identifying theorigin of a signal according to claims 1 to 3, characterised in that theidentification signal is placed in a randomly defined area on thescreen.
 5. System for identifying the origin of a signal according toclaims 1 to 3, characterised in that the identification signal isoverlaying the current image such as a background.
 6. Method foridentifying the origin of a signal broadcasted to a subscriber, thismethod comprising the following stages: encryption of a video signal bya main operator, transmission of this encrypted signal to several localoperators, decryption of the encrypted signal by a decryption module(MS1, MS2) of an enabled local operator (OPL1, OPL2) and disposal of thedecrypted signal, broadcasting of this signal to the subscribers of saidlocal operator (OPL1, OPL2), characterised in that it consists in:substituting by the decryption module all or part of the decryptedsignal with an identification signal identifying said decryption module.7. Method according to claim 6, characterised in that the identificationsignal replaces a part of the image formed by the decrypted signal inany region of the image.
 8. Method according to claim 6, characterisedin that the identification signal is overlaying the current image suchas a background.
 9. A method according to claims 6 to 8, characterisedin that it consists in sending an identification command by the mainoperator to one or several decryption modules.